Not necessarily, but something inside it got the BMS’s attention. The spectrum runs from a misreporting sensor (modest repair) through a weak cell section (pack service) to, rarely, pack replacement. The cap at 50% is the BMS being conservative while the question is open. Only Tesla’s diagnostics can place your car on that spectrum, which is why scheduling service is the entire to-do list.

Can I keep driving with BMS_a079?

Yes, Tesla says so explicitly. You’re driving a car with half its usual range, so plan charging stops accordingly, and remember it won’t start a charge above 50%, which makes road trips awkward but not impossible. What you shouldn’t do is ignore the alert for months: Tesla warns the maximum charge level and range may keep dropping without service.

Will a reboot or a deep charge cycle clear it?

No. The scroll-wheel reboot restarts the screens, not the battery management system, and the BMS won’t lift a protective cap because the display rebooted. Likewise, no pattern of charging or draining talks it out of the limit: the cap stays until service addresses what the BMS recorded. Treat any clearing trick you read about as folklore.

Is this covered by warranty?

If your car is within the 8-year battery and drive unit warranty (100,000–150,000 miles depending on model), a pack condition that caps charging is squarely the warranty’s territory, including the 70% capacity-retention guarantee if range has genuinely fallen. Out of warranty, costs range from sensing repairs in the hundreds to pack work in the thousands; get Tesla’s diagnosis first, then compare independent EV-pack specialists if needed.

BMS_A079 Tesla: Unable to Charge: Maximum Charge Level Reached (Reduced Maximum Charge Level)

Moderate

Quick answer

BMS_a079 means your Tesla’s battery management system has found a condition inside the high-voltage pack and capped charging at 50%. The car is still safe to drive: it just won’t charge above half. There is nothing to fix at home: this is a service alert, and the question that matters is warranty coverage.

What it means

The BMS (battery management system) is the computer that lives with your Tesla’s high-voltage pack, watching every cell group’s voltage and temperature. BMS_a079 means it has detected a condition internal to the pack that makes charging beyond 50% state of charge unwise, so it has imposed a hard cap: the car will charge normally when it’s below 50%, and simply won’t start a charge when it’s already above. Half your usable range is temporarily off the table.

This is a protective decision, not a malfunction of the charging hardware. Your home charger, the cable and the charge port are all fine: the pack itself reported something the BMS doesn’t like, and capping the charge level is how it keeps the situation from getting worse while you arrange service. Tesla’s guidance is plain: the car is OK to drive, but schedule service, because without it the maximum charge level and range may keep shrinking.

Everything behind this alert lives on the high-voltage side: the pack, its internal sensors, its cell groups. None of it is owner-serviceable, and no reboot or settings change lifts the cap. The genuinely useful work you can do is administrative: get Tesla’s remote diagnostics looking at the pack, and find out where you stand with the 8-year battery warranty.

BMS_A079 symptoms: what you'll notice

The touchscreen shows “Unable to charge: Maximum charge level reached” and charging stops (or won’t start) at about 50%
Charging works normally below 50% but refuses to begin when the battery is already above it
Displayed range is roughly half of what the car used to show after a full charge; the charge-limit slider can’t take effect above the cap

Common causes

Ordered from most to least likely.

1.

A condition internal to the high-voltage battery

Tesla’s own description, and honestly as specific as anyone outside their service system can be. The BMS has seen something, typically voltage behavior in part of the pack: that makes a full charge unwise.
2.

A weak or imbalanced cell group

The classic underlying story: one section of the pack drifts out of step with the rest, and the BMS caps the charge level so the weak section is never pushed to full. Confirming this takes Tesla’s diagnostics: it is not visible to an owner.
3.

A pack-internal sensing fault

Sometimes the cells are fine and a voltage-sense circuit inside the pack is misreporting. The BMS can’t tell trust-but-verify from real trouble on its own, so it caps charging either way. Same answer: service.

How to fix it: diagnosis, step by step

Cheapest and most likely checks first.

1 Confirm the behavior and keep driving normally

Verify the pattern (charges fine below 50%, won’t start above) and note when the alert first appeared. The car is OK to drive per Tesla’s own guidance; you’re living with half range, not a safety problem. Plan trips around the cap rather than testing it.
2 Book service in the app and let remote diagnostics run

Schedule service in the Tesla app and name the alert. The BMS logs everything it saw, and Tesla can usually pull and read those logs remotely before any visit, often telling you whether this is a sensing issue, a pack repair, or a pack replacement, and whether warranty covers it, without the car leaving your driveway.
3 Check your battery warranty position

The high-voltage battery is covered for 8 years (100,000–150,000 miles depending on model, with a 70% capacity-retention guarantee). A BMS-imposed charge cap on an in-warranty car is exactly the kind of thing that warranty exists for. Out of warranty, get Tesla’s written diagnosis before considering third-party pack specialists.
4 Do not attempt anything at the pack

There is no fuse to check, no connector to reseat, no DIY entry point here. The pack carries hundreds of volts and stores energy even when the car is “off.” Every credible repair path for BMS_a079 starts at Tesla Service: the only owner-side tools are the app and patience.

Parts & tools you may need

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Related codes

Frequently asked questions

What does code BMS_A079 mean?: BMS_a079 means your Tesla’s battery management system has found a condition inside the high-voltage pack and capped charging at 50%. It’s moderately serious: you can usually keep driving gently, but diagnose it soon.
Is my battery dying?: Not necessarily, but something inside it got the BMS’s attention. The spectrum runs from a misreporting sensor (modest repair) through a weak cell section (pack service) to, rarely, pack replacement. The cap at 50% is the BMS being conservative while the question is open. Only Tesla’s diagnostics can place your car on that spectrum, which is why scheduling service is the entire to-do list.
Can I keep driving with BMS_a079?: Yes, Tesla says so explicitly. You’re driving a car with half its usual range, so plan charging stops accordingly, and remember it won’t start a charge above 50%, which makes road trips awkward but not impossible. What you shouldn’t do is ignore the alert for months: Tesla warns the maximum charge level and range may keep dropping without service.
Will a reboot or a deep charge cycle clear it?: No. The scroll-wheel reboot restarts the screens, not the battery management system, and the BMS won’t lift a protective cap because the display rebooted. Likewise, no pattern of charging or draining talks it out of the limit: the cap stays until service addresses what the BMS recorded. Treat any clearing trick you read about as folklore.
Is this covered by warranty?: If your car is within the 8-year battery and drive unit warranty (100,000–150,000 miles depending on model), a pack condition that caps charging is squarely the warranty’s territory, including the 70% capacity-retention guarantee if range has genuinely fallen. Out of warranty, costs range from sensing repairs in the hundreds to pack work in the thousands; get Tesla’s diagnosis first, then compare independent EV-pack specialists if needed.